Nahid Shahriar Muhammad, Nahian Shahriar, Motalab Mohammad, Rakib Tawfiqur, Mojumder Satyajit, Islam Md Mahbubul
Department of Mechanical Engineering, Bangladesh University of Engineering and Technology Dhaka-1000 Bangladesh
Department of Mechanical and Chemical Engineering, Islamic University of Technology Board Bazar Gazipur-1704 Bangladesh.
RSC Adv. 2018 Aug 28;8(53):30354-30365. doi: 10.1039/c8ra04728f. eCollection 2018 Aug 24.
Silicene has become a topic of interest nowadays due to its potential application in various electro-mechanical nanodevices. In our previous work on silicene, fracture stresses of single crystal and polycrystalline silicene have been investigated. Existence of defects in the form of cracks reduces the fracture strength of silicene nanosheets to a great extent. In this study, an engineering way has been proposed for improving the fracture stress of silicene nanosheets with a pre-existing crack by incorporating auxiliary cracks symmetrically in a direction perpendicular to the main crack. We call this mechanism the "Failure shielding mechanism". An extensive molecular dynamics simulation based analysis has been performed to capture the atomic level auxiliary crack-main crack interactions. It is found that the main crack tip stress distribution is significantly changed with the presence of auxiliary cracks for loading along both armchair and zigzag directions. The effects of temperature and the crack propagation speed of silicene have also been studied. Interestingly, in the case of loading along the zigzag direction, SW defect formation is observed at the tip of main crack. This leads to a reduction of the tip stress resulting in a more prominent failure shielding in case of zigzag loading than in armchair loading. Moreover, the position and length of the cracks as well as the loading directions have significant impacts on the tip stress distribution. Finally, this study opens the possibilities of strain engineering for silicene by proposing an engineering way to tailor the fracture strength of silicene.
由于硅烯在各种机电纳米器件中的潜在应用，它如今已成为一个备受关注的话题。在我们之前关于硅烯的工作中，已经研究了单晶和多晶硅烯的断裂应力。裂纹形式的缺陷在很大程度上降低了硅烯纳米片的断裂强度。在本研究中，提出了一种工程方法，通过在垂直于主裂纹的方向上对称地引入辅助裂纹来提高已有裂纹的硅烯纳米片的断裂应力。我们将这种机制称为“失效屏蔽机制”。已进行了基于分子动力学模拟的广泛分析，以捕捉原子水平上辅助裂纹与主裂纹的相互作用。研究发现，对于沿扶手椅方向和锯齿方向加载，主裂纹尖端应力分布会因辅助裂纹的存在而发生显著变化。还研究了温度和硅烯裂纹扩展速度的影响。有趣的是，在沿锯齿方向加载的情况下，在主裂纹尖端观察到SW缺陷形成。这导致尖端应力降低，从而在锯齿加载情况下比扶手椅加载情况下产生更显著的失效屏蔽。此外，裂纹的位置和长度以及加载方向对尖端应力分布有显著影响。最后，本研究通过提出一种定制硅烯断裂强度的工程方法，为硅烯的应变工程开辟了可能性。
